mysql模拟队列_MySQL

mysql模拟队列

Java代码

-- 初始化数据

DROP TABLE IF EXISTS t_msg_queues;

CREATE TABLE t_msg_queues(

msg_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,

msg_content VARCHAR(255) NOT NULL,

owner_thread_id INT NOT NULL DEFAULT -1,

PRIMARY KEY (msg_id)

)ENGINE=INNODB DEFAULT CHARSET=utf8;

SET @maxRandom = POWER(10,6);

INSERT INTO `t_msg_queues`(`msg_content`)

VALUES (CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)))

,(CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)))

,(CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)))

,(CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)))

,(CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)))

,(CONCAT("cont_",CEIL(RAND()*@maxRandom))),(CONCAT("cont_",CEIL(RAND()*@maxRandom)));

-- 获取1条未处理的消息

SET SESSION autocommit=1;

SET @msgID = -1;

UPDATE t_msg_queues SET owner_thread_id=GREATEST(CONNECTION_ID() ,(@msgID:=msg_id)*0)

WHERE owner_thread_id=-1 ORDER BY msg_id LIMIT 1;

-- 此时@msgID如果为-1，代表没有待处理的消息，否则就代表本次需要处理的msg_id